INSTRUCTION MANUAL
CS445 Liquid Level Sensor
1/04
Copyright (c) 2004
Campbell Scientific, Inc.
The CS445 Pressure Transducer is manufactured by KWK Technologies. KWK’s
conditions of sale and return policy apply to these items.
Products may not be returned without prior authorization. To obtain an RMA number
contact KWK Technologies, Inc., phone (509) 466-5871, www.kwktechnologies.com.
NOTE: if the product has been exposed to hazardous media, it must be fully
decontaminated and neutralized prior to return to KWK.
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CS445 Table of Contents
PDF viewers note: These page numbers refer to the printed version of this document. Use
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1. Introduction.................................................................1
2. Specifications .............................................................1
3. Installation...................................................................2
3.1 Initial Inspection and Handling Guidelines...............................................2
3.2 Installation Guidelines..............................................................................3
4. Wiring ..........................................................................3
5. Programming Example...............................................3
5.1 Using ShortCut..........................................................................................4
5.2 Using CRBasic..........................................................................................4
5.3 Using Edlog..............................................................................................5
6. Maintenance................................................................6
6.1 Every Visit, At Least Monthly..................................................................6
6.2 Every Three Months .................................................................................6
6.3 Every Two to Three Years or on a Rotating Schedule..............................6
7. Troubleshooting Hints................................................7
Appendix
A. SDI-12 Transparent Mode......................................A-1
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1
CS445 Liquid Level Sensor
1. Introduction
This manual describes using the CS445, KWK Technologies’ SPXD-600
submersible pressure transducer with Campbell Scientific’s CR10(X), CR23X,
CR510, CR500 and CR200 series dataloggers. Information provided in the
manual includes datalogger-to-sensor connection, datalogger programming,
and maintenance requirements.
The CS445 Submersible Pressure Transducer is designed to provide reliable,
accurate water pressure/level measurements. This device is intended to
combine the excellent performance of the KWK analog pressure transmitter
with the convenience of the SDI-12 interface and commands. The result is a
device with performance exceeding the requirements of many water level
measurement applications and the simplicity of the three-wire SDI-12
connection scheme.
Combining the sensor, analog measurement and signal processing within a
single housing results in the integration of state-of-the-art sensor and
measurement technology. The 24 Bit A/D converter is auto calibrated prior to
each pressure measurement. A number of additional advanced measurement
techniques are employed to harness the best possible performance available
from today’s state-of-the-art pressure sensor technology. The Transducer
reverts to a low power sleep state between measurements. The auto calibration
and measurement cycle takes approximately 1 second. The CS445 responds to
the initiate measurement command, issued by a datalogger, indicating that 1
value will be ready in a maximum of 2 seconds.
The CS445 is specified for operation over the 0 – 50°C (32 – 122 °F)
temperature range. Standard pressure ranges include 0 – 5, 15, 30, 50 and 100
PSIG (Vented) as well as 30, 50 and 100 PSIA (Non-Vented).
The design utilizes an isolated silicon strain gauge sensor housed in a 316
Stainless Steel package to enhance reliability. The rugged construction makes
the CS445 suitable for water level measurement in irrigation applications,
water wells, lakes, streams and tanks. The cable incorporates a vent tube to
compensate for atmospheric pressure fluctuations and the jacket is made of
rugged polyurethane, designed to remain flexible and tough, even under harsh
environmental conditions.
2. Specifications
Electrical Specifications:
Excitation: 8 – 24 VDC
Operating Current: 0.36 mA quiescent, ~7 mA peak during
wake/measurement cycle
Operating Temperature Range: 0 – 60 °C, Nonfreezing
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Communications:
Protocol: SDI-12 Subset. Supported Commands: aM!,
aD!, aAb! (Firmware Version 1.0)
Output Units: PSI
Pressure Measurement Specifications:
Static Accuracy: 0.1 %Span (B.F.S.L.)
1
Thermal Shift Zero: +/- 1.0% Span
2
(5 PSIG Range)
+/- 0.40 % Span
2
(All Other Standard Ranges)
Thermal Shift Span: +/- 0.75 % Span
2
(5 PSIG Range)
+/- 0.40 % Span
2
(All Other Standard Ranges)
Mechanical Construction:
Diameter: 1.0”
Length: 13” (includes Flex Seal/Strain Relief)
Sensor Element and Body: 316 Stainless
Top Cap and End Cone Assembly: Delrin
Other wetted materials: Viton, Nylon, Buna-N
Cable:
Diameter: 0.290” Nominal
Shielded, 9 Conductor #24 AWG, Polyethylene Insulators
Jacket: Polyurethane
Integral Vent Tube
Cable Resistance: 0.026 Ohm/Ft Typ., TCR: 0.3%/°C
Notes:
1. Includes Linearity, Repeatability and Pressure Hysteresis at 25 °C.
2. 0 – 50 °C, Referenced to 25°C.
Specifications subject to change without notice.
3. Installation
3.1 Initial Inspection and Handling Guidelines
Upon receipt of the CS445, inspect the packaging for any signs of shipping
damage and, if found, report the damage to the carrier in accordance with
policy. The contents of the package should also be inspected and a claim filed
if any shipping related damage is discovered.
Care should be taken when opening the package not to damage or cut the cable
jacket. If there is any question about damage having been caused to the cable
jacket, a thorough inspection is prudent.
The model number and pressure range is etched on the housing. Check this
information against the shipping documentation to ensure that the expected
model number and range were received.
Gauge pressure (Vented) devices must always have a desiccant tube attached.
New desiccant is blue in color. As the desiccant material absorbs water vapor,
it begins to turn pink, and eventually white when fully expired. Desiccant
CS445 Liquid Level Sensor
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tubes should be inspected regularly (i.e., every two months) and historical
information will help to baseline desiccant replacement requirements for a
given application/climate.
Absolute pressure (Non-Vented) units do not require a desiccant chamber. If
the cable incorporates a vent tube, the vent tube is heat sealed at both ends
prior to shipment and must remain sealed.
Remember that although the CS445 is designed to be a rugged and reliable
device for field use, it is also a highly precise scientific instrument and should
be handled as such. There are no user serviceable parts and any attempt to
disassemble the device will void the warranty.
3.2 Installation Guidelines
The CS445 is designed for water level measurement. Typical applications
include agricultural water level/flow, water wells, lakes, streams and tanks. If
the device is to be installed in a liquid other then water or in contaminated
water, check the compatibility of the wetted materials.
The Transducer may be installed in any position but it is calibrated and tested
in the vertical orientation, as it would normally be suspended.
Never suspend the transducer from the connections at the top end of the cable.
When suspending the device, in a well for example, a proper strain relief
should be attached around the cable jacket and properly secured at the well
head.
Although the cable jacket is made from a thick, tough polyurethane formation,
care should be taken to avoid cable damage. Further, sharp bends or excessive
pinching of the cable can cause damage and may pinch off the vent tube
causing measurement errors in the case of gauge pressure (Vented) devices.
Do not drop the instrument or allow it to “free fall” down a well as this may
damage the device.
Never attempt to disassemble the transducer as this will void the warranty.
4. Wiring
Color Function CR200 Series CR23X, CR10(X),
CR510, CR500
Red + Power. 8 to 24 VDC Battery + 12V
Black Ground G G
Brown SDI-12 Data Line C1/SDI-12 Control Port 1-8
Clear Shield. Not connected
to transducer body
GG
5. Programming Example
The CS445 uses an SDI-12 compatible hardware interface and supports a
subset of the SDI-12 commands. The most commonly used command is the
aM! command, issued by the datalogger. Here, ‘a’ represents the sensor
address (0 – 9). The communication sequence begins with the datalogger
CS445 Liquid Level Sensor
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waking the sensor and issuing the aM! command. The transducer responds to
the logger indicating that one measurement will be ready within two (2)
seconds. Subsequent communications handle data reporting from the sensor to
the datalogger.
Sensor Address
The CS445 is shipped from the factory with a preset SDI-12 address of 0. This
can be changed using the SDI-12 command ‘aAb!’ and the suggested method is
to use the SDI-12 Transparent Mode in a logger. See Appendix A for details
on Transparent Mode.
5.1 Using ShortCut
ShortCut is the easiest and typically the preferred method for programming the
datalogger. ShortCut generates a wiring diagram that shows how to connect
the pressure transducer to your datalogger.
The sections that immediately follow are for CRBasic, Edlog and
Keyboard/Display users. ShortCut users can jump ahead to the
Maintenance section (page 6).
5.2 Using CRBasic
In the CR200 Series dataloggers, Instruction SDI12Recorder is used to read
SDI-12 Sensors. A multiplier of 1.0 and an offset of 0.0 yields water level in
units of pounds per square inch (psi). For units of feet use a multiplier of 2.31
and an offset of 0.0.
The SDI12Recorder instruction has the following form:
SDI12Recorder(Destination, Output String, Multiplier, Offset)
Wiring for example program
Red Battery +
Black G
Brown C1/SDI-12
Clear G
Sample Program for CR200 Series Datalogger
'CR200 Series
'Declare the variable for the water level measurement
Public Level
'Define a data table for 60 minute maximum and minimums
DataTable(Hourly,True,-1)
DataInterval(0,60,Min)
Maximum(1,Level,0,0)
Minimum(1,Level,0,0)
EndTable
‘Read sensor(s) every 60 seconds
NOTE
CS445 Liquid Level Sensor
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BeginProg
Scan(60,Sec)
' Code for SDI-12 measurements:
SDI12Recorder(Level,0M!,1,0)
‘ Call the data table:
CallTable(Hourly)
NextScan
EndProg
5.3 Using Edlog
The following is an example of the P105 SDI-12 Sensor instruction used by
array-based dataloggers to interrogate an SDI-12 sensor.
Use Instruction 105 to read the CS445. Your datalogger manual has a detailed
explanation of Instruction 105.
Wiring for example program
Red 12V
Black G
Brown C1
Clear G
;{CR10X}
;
*Table 1 Program
01: 60 Execution Interval (seconds)
1: SDI-12 Recorder (P105)
1: 0 SDI-12 Address
2: 0 Start Measurement (aM0!)
3: 1 Port ;this is where the brown wire is connected
4: 1 Loc [ Level ]
5: 1.0 Mult
6: 0.0 Offset
*Table 2 Program
02: 0.0000 Execution Interval (seconds)
*Table 3 Subroutines
End Program
After this command is executed, the input location within the logger called
“Pressure” holds the measured pressure, reported in PSI. This result may be
further processed within the logger or stored to final storage memory. Note
that Port 1 specifies that the SDI-12 data line is to be connected to Port C1.
Other ports may be selected. The Multiplier and Offset can be changed to
scale the result or perform unit conversions (e.g., Depth = 2.31 * Pressure).
CS445 Liquid Level Sensor
6
6. Maintenance
Periodic evaluation of the desiccant is vital for keeping the vent tube dry. To
assess the effectiveness of the desiccant, use one of the following:
• An indicating desiccant that changes color when it’s losing its drying
power
• An enclosure humidity indicator such as our #6571 humidity indicator
card
6.1 Every Visit, At Least Monthly
• Collect data
• Visually inspect wiring and physical conditions
• Check indicating desiccant or enclosure humidity indicator; service
desiccant if necessary
• Check battery condition (physical and *6 mode of the datalogger)
• Check all sensor readings (*6 mode of the datalogger); adjust transducer
offsets if necessary
• Check recent data (*7 mode of the datalogger)
• Perform routine maintenance suggested by manufacturers
See datalogger manual for more information on *6 and *7
modes.
6.2 Every Three Months
• Change batteries (as needed--may be less often)
• Replace enclosure desiccants
• Check calibration of all sensors
• Inspect probe cable conditions for deterioration or damage
• Check wire connections ensuring they are still secure
6.3 Every Two to Three Years or on a Rotating Schedule
Send the transducers to the factory or laboratory for inspection and have them
serviced and/or replaced as needed.
NOTE
CS445 Liquid Level Sensor
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7. Troubleshooting Hints
Problem:
Unit will not respond when attempting serial communications.
Suggestion:
Check the power (Red is +V and Black is Ground ) and signal (Brown is SDI-
12 Data) lines to ensure proper connection to the logger. Check the logger
program to ensure that the same port the SDI-12 data line is connected to is
specified in the measurement instruction.
Problem:
Transducer appears to be operating properly but data shows a periodic or cyclic
fluctuation not attributable to water level changes.
Suggestion:
A kinked or plugged vent tube will not effectively vent a gauge pressure
(Vented) type of device. Normal changes in barometric pressure will appear as
water level fluctuations and these types of errors are typically on the order of 1
foot of water level. If the desiccant chamber has not been properly maintained,
water may have condensed in the vent tube and the device should be returned
to the factory for service.
Note that errors in uncompensated depth measurement using absolute (Non-
Vented) devices are expected and may or may not be significant, depending on
the application. A barometric pressure transducer can be used to provide
compensation data, effectively eliminating error due to barometric fluctuations.
CS445 Liquid Level Sensor
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A-1
Appendix A. SDI-12 Transparent Mode
See Section 9 of the datalogger manual for more details. The datalogger must
be powered up, programmed with a P105 instruction, and have the CS445
connected to it.
1. Enter terminal emulator mode in LoggerNet or PC208W software.
2. On the computer keyboard strike the Enter key a few times until the “*”
datalogger telecommunications prompt appears.
3. The datalogger telecommunications command to enter SDI-12 transparent
mode is “nX<Enter>” where n is the control port being used for SDI-12.
In this example the selected control port is C1, so the command would be
“1X<Enter>”. In response, the datalogger opens the link to control port 1
and responds with a prompt. CR10X and CR500 dataloggers reply with
“entering SDI-12”. CR10s reply with a “<” sign.
4. Now check for response from the sensor with address zero by typing the
SDI-12 Identify command “0I!<Enter>” (that’s a zero, not the letter O).
The sensor should respond with an identification string similar to
“010KWKTechnologiesSPXD-600SDI1.3-1.00.” Note that the SDI-12
standard allows for multiple probes to be connected to one datalogger
control port. If you have another SDI-12 probe on C1 that has address 7,
you could issue the identify command “7I!<Enter>”.
5. At this point you may change the CS445’s address following this
example: To change the address from 0 to 1 type in “0A1!<Enter>” .
To exit SDI-12 transparent mode, type any invalid SDI-12 command string.
The simplest would be a blank line such as “<Enter>”.
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